Silicon Electro-optic Orbital Angular Momentum Sign Modulator for Photonic Integrated Circuit

In this paper, we propose a silicon-based electro-optic (EO) modulator which can modulate a sign of a topological charge number l of |l|=1 orbital angular momentum (OAM) mode. The proposed EO modulator consists of position-dependent doped Si waveguide core and undoped SiO2, cladding, which enables control of the effective index and propagation loss of two OAM constitutive eigenmodes. The modulator functions as OAM mode maintaining waveguide at – 0.33V and as topological charge sign inverter at 10V. The output OAM mode purity is calculated through electric field distribution, showing high purity of |l|>0.92 in both cases.